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首页> 外文期刊>Biochemistry >Cryptoregiochemistry of the delta11-myristoyl-CoA desaturase involved in the biosynthesis of Spodoptera littoralis sex pheromone.
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Cryptoregiochemistry of the delta11-myristoyl-CoA desaturase involved in the biosynthesis of Spodoptera littoralis sex pheromone.

机译：delta11-肉豆蔻酰-CoA去饱和酶的密码子区域化学参与斜纹夜蛾性信息素的生物合成。

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摘要

Many moth species biosynthesize their sex pheromones by the action of unique desaturases. These membrane-bound family of enzymes are especially interesting, since some of them produce (E)-unsaturated fatty acids either exclusively or along with the (Z)-isomer. In this article we present the first mechanistic study on one of these enzymes, namely, the Delta11-myristoyl-CoA desaturase of the moth Spodoptera littoralis. Intermolecular primary isotope effect determinations were performed in competition experiments. The unusual use of odd-number fatty acids, tridecanoic acid and deuterium-labeled tridecanoic acid, in these experiments showed the existence of a large isotope effect for the carbon-hydrogen bond cleavage at C11, but no isotope discrimination occurred in the removal of C12-H. The results of the competitive experiments are consistent with the hypothesis that this Delta11-desaturase involves a first slow, isotope-sensitive C11-H bond cleavage, with probable formation of an unstable intermediate, followed by a second fast C12-H bond removal. We suggest that a single enzyme may be responsible for the formation of both (Z)- and (E)-11-tetradecenoic acids by accommodating both gauche and anti conformers of the substrate, respectively. It is also possible that two mechanistically identical discrete enzymes are involved in each desaturation. In this case, the geometry of the resulting double bond would result from the different conformation adopted by the acyl substrate at each enzyme active site.
机译：许多蛾类通过独特的去饱和酶的作用来生物合成其性信息素。这些与膜结合的酶家族特别有趣，因为其中一些酶仅或与（Z）异构体一起产生（E）-不饱和脂肪酸。在本文中，我们对这些酶之一进行了首次机理研究，即蛾蛾斜纹夜蛾的Delta11-肉豆蔻酰-CoA去饱和酶。在竞争实验中进行了分子间一级同位素效应的测定。在这些实验中，奇数脂肪酸，十三烷酸和氘标记的十三烷酸的不寻常使用显示出在C11处存在碳氢键断裂的大同位素效应，但在去除C12时没有同位素歧视-H。竞争性实验的结果与以下假设相吻合：该Delta11-去饱和酶涉及第一个缓慢的，对同位素敏感的C11-H键缓慢裂解，可能形成不稳定的中间体，然后第二个快速去除C12-H键。我们建议单个酶可能负责通过分别容纳基体和反构象体的（Z）-和（E）-11-十四碳烯酸的形成。每个去饱和中也可能涉及两种在机械上相同的离散酶。在这种情况下，所得双键的几何形状将由酰基底物在每个酶活性位点处采用的不同构象产生。

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